M61 was probably first used in combat by British Lees and Grants at Gazala in May 1942. The first US use was by Marine M3 GMCs at Guadalcanal in fall 1942. It is doubtful any M61 made it to the M3 GMCs in the Philippines. It was supplied to all the Allies in addition to US Forces. M61 remained in use through the end of the war. Essentially all 75mm gun armor piercing ammunition expended in combat by US forces during WW2 was M61 or M61A1.